Monthly Archives: July 2005

Notes: Bias in computer systems

Friedman, B., & Nissanbaum, H.  (1996). Bias in computer systems.  ACM Transactions on Information Systems, 14(3), 330-347.

 

In this article Friedman and Nissenbaum look at bias in software systems. Although the word bias can cover a number of related concepts, the definition used here is something that systematically and unfairly discriminates toward one party or against another. The authors see three main classes of bias in computer systems: Preexisting bias, when an external bias is incorporated into a computer system, either through individuals who have a hand in designing the system or via the society the software was created in; Technical bias, where technical considerations bring about bias (from limitations, loss of context in algorithms, random number generation, or formalization of human constructs); and Emergent bias, where bias emerges after design when real users interact with the system (for example, when new information is available but not in the design, or when systems are extended to new user groups). A number of illustrative examples are given, and the authors look at a number of specific software systems and point out existing or potential biases. One of the systems is the The National Resident Match Program (NRMP), used to match med school graduates to hospitals. In this system, if a student’s first choice of hospital and hospital’s first choice of student do not match, the students’ second choices are run against the hospitals’ first choices. Overall, the result favors the hospitals. Two steps are proposed to rectify bias – diagnosis and active minimization of bias.

This is an extremely interesting subject, and and I doubt most users and programmers are any more aware of it now than they were in 1996. One more recent article, (http://web.mit.edu/21w.780/Materials/douglasall.html) which sought to turn literary criticism toward video games by pointing out cultural biases, also mentions the lack of study in this area. With so many people spending so much of their day interacting with software, why do these kinds of articles seem so few and far between? On the other hand, the particular examples chosen are illustrative but not very current. All three of the systems were large-scale, mainframe-type software that users interacted with in a very small sense. Would the risk of bias be even greater for a system which is largely a user interface?

One clear implication is shown in the diagnosis stage of removing bias—to find technical and emergent bias, designers are told to imagine the systems as they will actually be used and as additional user groups adopt them, respectively. So the charge is one-third ‘know thyself’ and two-thirds ‘know the users.’ The very notion of looking for bias is probably foreign to many user interface designers (in fact, few of the programmers I’ve met are even aware that accessibility guidelines exist for blind, deaf, and other users). The authors’ proposal that professional groups offer support to those designers who detect bias and wish to fight it is a nice thought but doubtful. Few programming or UI organizations can exert any kind of pressure or drum up much bad publicity, or if they can, I haven’t heard of it (which I suppose means they can’t).

Notes: Web site usability, design, and performance metrics

Palmer, J.W. (2002). Web site usability, design, and performance metrics. Information Systems Research, 13(2), 151-167.

In this study Palmer looks at three different ways to measure web site design, usability and performance. Rather than testing specific sites or trying out specific design elements, this paper looks at the validity of the measurements themselves. Any metrics must exhibit at least construct validity and reliability—meaning that the metrics must measure what they say they measure, and they must continue to do so in other studies. Constructs measured included download delay, navigability, site content, interactivity, and responsiveness (to user questions). The key measures of the user’s success with the web site included frequency of use, user satisfaction, and intent to return. Three different methods were used: a jury; third-party rankings (via Alexa), and a software agent (WebL). The paper examine the results of three studies, one in 1997, on in 1999, and one in 2000, involving corporate web sites. The measures were found to be reliable, meaning jurors could answer a question the same way each time, and valid, in that different jurors and methods agreed on the answers to questions. In addition, the measures were found to be significant predictors of success.

This is an interesting article because in my experience, usability studies are often all over the place, with everything from cognitive psychology and physical ergonomics to studies of server logs to formal usability testing to “top ten usability tips” lists. Some of this can be attributed to the fact that it is a young field, and some of it is due to the different motive fueling research (commercial versus academic). One thing in the article I worry about, however, is any measure of “interactivity” as a whole. Interactivity is not a simple concept to control, and adding more interactivity is not always a good idea. Imagine a user trying to find the menu on a restaurant’s web site—do they want to be personally guided through it via an interactive Flash cartoon of the chef, or do they want to just see the menu? Palmer links interactivity to the theory of media richness, which has a whole body of research behind it that I am no expert on. But I would word my jury questionnaires to reflect a rating of appropriate interactivity.

The most important impact of this study is that it helps put usability studies on a more academically sound footing. It is very important to have evidence that you are measuring what you think you are measuring. It would be interesting to see if other studies have adopted these particular metrics because of the strong statistical evidence in this study.

The most straight-forward metric, download delay, is also one that has been discounted lately. The thought is that with so many users switching to broadband access, download speed is no longer the issue it used to be. This is especially false for sites with information seeking interfaces, which are often very dynamic and rely on database access. No amount of bandwidth will help if your site’s database server is overloaded.